score = float(input('请输入成绩: '))

if score >= 90 and score <= 100:

  print('对应的等级是:A')

elif score >= 80 and score < 90:

  print('对应的等级是:B')

elif score >= 70 and score < 80:

  print('对应的等级是:C')

elif score >= 60 and score < 70:

  print('对应的等级是:D')

else :
   print('对应的等级是:E')

